使用 Apache POI 在 Excel 上编写二维整数数组

Question

I am trying to export 2d arrays of integers to Excel. Precisely, I need to export 2 arrays of integers of the same dimension. I previously installed the libraries for using Apache POI in Java using Eclipse IDE.

My idea is to pass as parameters for the writeExcel method 2 arrays of integers (arrayOne and arrayTwo) and get as a result an Excel file where 2 matrices were written with their respective values. For example, for the case where both matrices are from 5x5 dimension this is what I tried:

import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class ExportToExcel {
    
    public static void WriteExcel(int[][] arrayOne, int[][] arrayTwo) {
        
        String fileName = "MyExcelFile.xlsx";
        String sheet = "5x5";
        
        XSSFWorkbook book = new XSSFWorkbook();
        XSSFSheet hoja1 = book.createSheet(sheet);
        
        // Header of the de Excel File
        String[] header = new String[] {"col 0", "col 1", "col 2", "col 3", "col 4"}; 
    
        // Fill the Excel File
        for (int i = 0; i <= ruta.length; i++) {
            
            XSSFRow row = hoja1.createRow(i);
            
            for (int j = 0; j < header.length; j++) {
                
                if (i == 0) {
                    
                    XSSFCell cell = row.createCell(j);
                    cell.setCellValue(header[j]);
                    
                }
                
                    else {
                    
                        XSSFCell cell = row.createCell(j);
                        // some code here??
                        
                    }
                
            }
        }
        
    }

}

Clearly, in the previous code are missing parts that I don't know how to include. Thus, if I pass as a parameters to the method the following 2 matrices:

arrayOne: [[2, 0, 1, 3, 4], [0, 1, 2, 3, 4], [0, 2, 1, 4, 3], [2, 1, 0, 4, 3], [2, 0, 1, 3, 4]]
arrayTwo: [[1, 1, 4, 1, 1], [4, 4, 0, 4, 4], [0, 0, 1, 0, 0], [2, 3, 3, 3, 3], [3, 2, 2, 2, 2]]

The expected result in Excel must be something like:

Thanks in advance if anyone can help me with this question.

Answer 1

You should iterate through the whole excel sheet and then check if you are in the desired cell, write the appropriate value.

One way to do this, is with CellReference . With that you can reference to a cell and then take its row/col index an write on it.

For example:

CellReference A1 = new CellReference("A1");

int row = cr.getRow();
int col = cr.getCol();

Now you got the index for row/col of A1 and you can write on this position like this:

Row row1 = ((sheet.getRow(row)==null) ? sheet.createRow(row) : sheet.getRow(row));

With the line above you check if the row exists, and if not, then you create one.

Cell cell;
if (row1.getCell(col) == null) {
    cell = row1.createCell(col);
} else {
    cell = row1.getCell(col);
}

With the above, you check the specific cell on the specific row if its empty, and if it is then you create a new one, else you the its reference.

Now, you are ready to write on A1 cell. Simply do:

cell.SetCellValue("arrayOne");

So now, just use row and col that represent the index for row/col in your sheet and write in the cells of your choice.

For example by doing col+=1 you getting B1 and by repeating the above code in a for loop and increment every time the col and/or row index inside your loop, you can write the arrays in the way you want on your sheet.

Please feel free to ask me for extra clarification.